Femoral Nerve Localizer and Needle Guide for Spine Surgery

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Solution Overview

Problem

During minimally invasive spine surgery, there is a need for a reliable method to monitor the proximity, health, and status of nearby nerves, particularly the femoral nerve, to prevent compression and neural compromise, as existing methods lack a quick and effective means to detect changes in neurogenic and myogenic responses.

Innovation Solution

A combination femoral nerve localizer and needle placement guide instrument equipped with transcutaneous stimulation electrodes and needle guides, allowing for precise localization and stimulation of the femoral nerve, with the ability to record neuromuscular responses, enabling advanced neuromonitoring capabilities during surgical procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If minimally invasive spine surgery is performed, then patient morbidity and recovery time are reduced, but the risk of neural compromise from undetected nerve compression increases

Engineering Contradiction:

Improvepatient morbidityVSAvoidnerve safety

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The system continuously monitors nerve status during surgery by delivering stimulation signals through electrodes and detecting neurogenic responses. Real-time feedback alerts the surgeon when nerve compression is detected, allowing immediate intervention to prevent permanent neural damage while maintaining the benefits of minimally invasive approach

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Electrodes are positioned as intermediary elements between the surgical retractor and the femoral nerve. These electrodes serve as a mediator to detect nerve compression before mechanical contact occurs, enabling preventive measures to be taken during the minimally invasive procedure

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If real-time nerve monitoring is implemented, then neural compromise is prevented, but device complexity and cost increase

Engineering Contradiction:

Improvenerve safetyVSAvoidmonitoring system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The monitoring system merges multiple functions into integrated components: stimulation electrodes, response detection electrodes, and signal processing are combined in a unified system. The surgical retractor assembly integrates both mechanical retraction and neural monitoring capabilities, reducing overall system complexity while maintaining comprehensive nerve protection

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The electrodes and monitoring system are designed with multi-functionality to justify the added complexity. The same electrode assembly provides both stimulation and response detection, and the system can monitor multiple nerves simultaneously, making the increased device complexity worthwhile through enhanced versatility and comprehensive monitoring coverage

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If stimulation electrodes are placed on retractor blades, then nerve proximity is detected, but the electrodes may inadvertently contact and compress nerves

Engineering Contradiction:

Improvenerve proximity detectionVSAvoidnerve compression

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

Neural monitoring is activated before the retractor blade contacts the nerve. By continuously monitoring for neurogenic responses during the approach and positioning phases, the system detects nerve proximity in advance, allowing the surgeon to adjust positioning before compressive contact occurs

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The monitoring system serves as a protective cushion by providing early warning of nerve compression. When stimulation electrodes detect nerve proximity through neurogenic responses, the system alerts the surgeon to prevent further compression, effectively cushioning against the harmful effect of electrode-nerve contact before it occurs

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution provides real-time monitoring of nerve status, reducing the risk of neural compromise by allowing for optimal placement of needles and electrodes, thereby enhancing the safety and effectiveness of minimally invasive spine surgery.

Implementation Method 1

One or more stimulating electrodes may be provided on the distal tip of each component of the surgical access system

Methodology Applied

Scientific EffectElectrical stimulation: Electric Field

Implementation Method 2

Nerve monitoring may be performed while advancing each of the dilation and retraction assemblies to the target site to detect the presence of, and thereby avoid, nerves lying in the trans-psoas path to the target site

Methodology Applied

Scientific EffectElectrical signal detection: Conduction (electrical)

Data Source

PatentUS9757067B1Systems and methods for performing neurophysiologic monitoring during spine surgery

Publication Date: 2017.09.12 NUVASIVE INC

AI summary

This disclosure describes a surgical instrument comprising a combination femoral nerve localizer and needle placement guide instrument. The instrument may be used with a neuromonitoring system to localize and monitor the femoral nerve during a spinal procedure.